e75ba1d5c4
Extend the ino_t, dev_t, nlink_t types to 64-bit ints. Modify struct dirent layout to add d_off, increase the size of d_fileno to 64-bits, increase the size of d_namlen to 16-bits, and change the required alignment. Increase struct statfs f_mntfromname[] and f_mntonname[] array length MNAMELEN to 1024. ABI breakage is mitigated by providing compatibility using versioned symbols, ingenious use of the existing padding in structures, and by employing other tricks. Unfortunately, not everything can be fixed, especially outside the base system. For instance, third-party APIs which pass struct stat around are broken in backward and forward incompatible ways. Kinfo sysctl MIBs ABI is changed in backward-compatible way, but there is no general mechanism to handle other sysctl MIBS which return structures where the layout has changed. It was considered that the breakage is either in the management interfaces, where we usually allow ABI slip, or is not important. Struct xvnode changed layout, no compat shims are provided. For struct xtty, dev_t tty device member was reduced to uint32_t. It was decided that keeping ABI compat in this case is more useful than reporting 64-bit dev_t, for the sake of pstat. Update note: strictly follow the instructions in UPDATING. Build and install the new kernel with COMPAT_FREEBSD11 option enabled, then reboot, and only then install new world. Credits: The 64-bit inode project, also known as ino64, started life many years ago as a project by Gleb Kurtsou (gleb). Kirk McKusick (mckusick) then picked up and updated the patch, and acted as a flag-waver. Feedback, suggestions, and discussions were carried by Ed Maste (emaste), John Baldwin (jhb), Jilles Tjoelker (jilles), and Rick Macklem (rmacklem). Kris Moore (kris) performed an initial ports investigation followed by an exp-run by Antoine Brodin (antoine). Essential and all-embracing testing was done by Peter Holm (pho). The heavy lifting of coordinating all these efforts and bringing the project to completion were done by Konstantin Belousov (kib). Sponsored by: The FreeBSD Foundation (emaste, kib) Differential revision: https://reviews.freebsd.org/D10439
187 lines
5.0 KiB
Groff
187 lines
5.0 KiB
Groff
.\" Copyright (c) 1989, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)getdirentries.2 8.2 (Berkeley) 5/3/95
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.\" $FreeBSD$
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.\"
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.Dd May 3, 1995
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.Dt GETDIRENTRIES 2
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.Os
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.Sh NAME
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.Nm getdirentries ,
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.Nm getdents
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.Nd "get directory entries in a file system independent format"
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/types.h
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.In dirent.h
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.Ft ssize_t
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.Fn getdirentries "int fd" "char *buf" "size_t nbytes" "off_t *basep"
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.Ft ssize_t
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.Fn getdents "int fd" "char *buf" "size_t nbytes"
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.Sh DESCRIPTION
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The
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.Fn getdirentries
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and
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.Fn getdents
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system calls read directory entries from the directory
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referenced by the file descriptor
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.Fa fd
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into the buffer pointed to by
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.Fa buf ,
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in a file system independent format.
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Up to
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.Fa nbytes
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of data will be transferred.
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The
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.Fa nbytes
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argument must be greater than or equal to the
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block size associated with the file,
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see
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.Xr stat 2 .
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Some file systems may not support these system calls
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with buffers smaller than this size.
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.Pp
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The data in the buffer is a series of
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.Vt dirent
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structures each containing the following entries:
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.Bd -literal -offset indent
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uint32_t d_fileno;
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uint16_t d_reclen;
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uint8_t d_type;
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uint8_t d_namlen;
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char d_name[MAXNAMLEN + 1]; /* see below */
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.Ed
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.Pp
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The
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.Fa d_fileno
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entry is a number which is unique for each
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distinct file in the file system.
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Files that are linked by hard links (see
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.Xr link 2 )
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have the same
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.Fa d_fileno .
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The
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.Fa d_reclen
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entry is the length, in bytes, of the directory record.
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The
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.Fa d_type
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entry is the type of the file pointed to by the directory record.
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The file type values are defined in
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.Fa <sys/dirent.h> .
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The
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.Fa d_name
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entry contains a null terminated file name.
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The
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.Fa d_namlen
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entry specifies the length of the file name excluding the null byte.
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Thus the actual size of
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.Fa d_name
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may vary from 1 to
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.Dv MAXNAMLEN
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\&+ 1.
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.Pp
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Entries may be separated by extra space.
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The
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.Fa d_reclen
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entry may be used as an offset from the start of a
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.Fa dirent
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structure to the next structure, if any.
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.Pp
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The actual number of bytes transferred is returned.
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The current position pointer associated with
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.Fa fd
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is set to point to the next block of entries.
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The pointer may not advance by the number of bytes returned by
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.Fn getdirentries
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or
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.Fn getdents .
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A value of zero is returned when
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the end of the directory has been reached.
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.Pp
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The
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.Fn getdirentries
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system call writes the position of the block read into the location pointed to by
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.Fa basep .
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Alternatively, the current position pointer may be set and retrieved by
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.Xr lseek 2 .
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The current position pointer should only be set to a value returned by
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.Xr lseek 2 ,
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a value returned in the location pointed to by
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.Fa basep
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.Po Fn getdirentries
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only
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.Pc
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or zero.
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.Sh RETURN VALUES
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If successful, the number of bytes actually transferred is returned.
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Otherwise, -1 is returned and the global variable
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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The
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.Fn getdirentries
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system call
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa fd
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argument
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is not a valid file descriptor open for reading.
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.It Bq Er EFAULT
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Either
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.Fa buf
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or
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.Fa basep
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point outside the allocated address space.
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.It Bq Er EINVAL
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The file referenced by
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.Fa fd
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is not a directory, or
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.Fa nbytes
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is too small for returning a directory entry or block of entries,
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or the current position pointer is invalid.
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.It Bq Er EIO
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An
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.Tn I/O
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error occurred while reading from or writing to the file system.
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.El
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.Sh SEE ALSO
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.Xr lseek 2 ,
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.Xr open 2
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.Sh HISTORY
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The
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.Fn getdirentries
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system call first appeared in
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.Bx 4.4 .
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The
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.Fn getdents
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system call first appeared in
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.Fx 3.0 .
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